Automatic controller



Jul 4, 1939.

o. WUNSCHE AUTOMATIC CONTROLLER File'd Ilay 9, 1938 Invgnton Otto Wunsche, by

5M His Attorney Patented July 4, 1939 PATENT OFFICE AUTOMATIC CONTROLLER Otto Wiinsche, Berlin, Germany, assignor to General Electric Company, a corporation of New York Application May 9, 1938, Serial No. 206,951 In Germany May 13, 1937 10 Claims.

This invention relates to automatic controllers, more specifically to controllers which are stepped from one position to another in response to the current in the control circuit, such as the circuit 5 of a motor, and has for its object the provision of simple and inexpensive current responsive means for controlling the stepping of the controller from one position to the next.

With automatically stepping controllers, a stepping relay Or a current limiter is generally used in order to advance the switch drum to the next position when the motor current has decreased to a predetermined value. A ratchet wheel and latch usually serve as mechanical means for controlling the stepping, the latch being actuated by a special magnet controlled by the currentresponsive relay to lift the latch over a ratchet tooth whereupon the switch drum is free to be moved by a spring or the like to the next switch 20 position. The construction of such switch gears is however, rather complicated, and furthermore, such switch gears are noisy in operation and an noying to the passengers by the continual striking of the latch.

25 The controller according to the invention hereinafter described as particularly suitable for trolley busses avoids these disadvantages, and is characterized in that the switch drum is provided with a rotating magnet wheel, the pole teeth of which 30 move past a holding magnet excited by the motor current, which magnet releases to permit further rotation of the switch drum only when the motor current has attained a lower limiting value.

For a more complete understanding of my in- 35 vention reference should be had to the accompanying drawing, Fig. 1 of which is a fragmentary elevation view of controller means embodying this invention; Fig. 2 is a plan view of Fig. 1 showing in addition the controller drum; Fig. 3 is a front 40 view of the two-part operating pedal for the cont'roller; Fig. 4 is a diagram of connections for the control magnet; Fig. 5 shows typical acceleration curves of a motor; Fig. 6 is a fragmentary View showing a modified form of magnetic stepping 45 control means; while Fig. 7 is a diagrammatic view showing a modified control for the stepping magnet.

Referring to the drawing, in one form of the inventtion a supporting shaft I is provided which 50 is fixed rigidly in bearing blocks II and 12 so as to be held thereby against rotation. This shaft 16 carries the switch drum is and the rotating magnet wheel i made of magnet COIB'lI'OD and forming a field structure firmly connected to the 155 drum, as well as the gear wheel 16. by means of which the drum is rotated on the shaft In. As shown, this gear wheel 16 is rotatably mounted on the shaft l0 and is connected to the magnet wheel ill by means of a helical spring I! encircling the shaft I0. Also, the drum [3 is connected to the 5' bearing block II by a second helical spring I8. This spring 18 biases the switch drum back to the Zero or starting position when the control levers l9 and 20, as shown asa two part pedal, are released, while the spring I! is tensioned when the pedals are depressed to such an extent that the switch drum can be rotated by the spring to the last driving position. Coinciding with the zero posi-. tion of the switch drum, a magnet core 21 forming a stationary field structure is arranged which is excited by a coil 22 through which the motor current flows.

As shown, the pedals l9 and are mounted for movement about a fixed pivot 23, an intermediate point of the pedal lever being connected 20 by a link 24 to a gear sector 25 which meshes with the driving gear l6.

When the pedals i9 and 20 are pressed downward and thereby the spring 11 tensioned, the rotating magnet wheel [5 and the switch drum. I3 25 rotate in a counterclockwise direction as viewed in Fig. 1. The magnet wheel I5 is provided around its periphery with a plurality of teeth 26 at suitably spaced intervals, each of which forms an armature or pole piece for the magnet formed 30 by the coil 22 and core 2!. Shortly before it reaches the first driving position, the switch drum i3 closes the current circuit of the driving motor or motors so that the coil 22, which may be divided into several holding magnets with corresponding 3-5 pole teeth 26 opposite them, is energized by the current in the motor circuit and the further ro'-' tation of the drum is stopped by a tooth 26 being held by the coil 22 until the motor current has decreased to a predetermined low value. This'proc- 4 ess is repeated with each successive pole tooth or switching position.

With the usual number of starting steps the dif-' ference between stepping motor current and peak motor current, currents A and B, Fig. 5, is too small to eifect in coil 22 the release and holding of the corresponding pole teeth 26 by the magnet.

In order to increase this difference in the current values in percentage, a second winding 22a is provided which. is connectedto the constant potentia-l of the supply source and is mounted .on the core 2| with the coil v22 so as to oppose the coil 22. If the current or magnetic effect of this opposing winding 22a is equal to the value C, Fig; 5, the effective variation in the current of the magnet between release and holding is altered in the percentage from D to E, Fig. 5, the ratio of which assures reliable operation.

The opposing coil 22a makes it now possible to alter the starting acceleration in a simple manner in accordance with the wish of the driver. If the coil 22a is more strongly excited, for example if its excitation is increased to the value F, Fig. 5, then the current value at which the stepping oi the switch drum |3 takes place is also shifted in the same degree with corresponding increase in the rate of acceleration. This transfer to a higher rate of acceleration is performed by the driver increasing the pressure on the pedals l9 or 20 after the complete depression of the pedals,

To effect this an arm 27 is provided on the pedal lever, which arm 21 presses, when the pedal is fully depressed, on the ram 28 of a carbon plate or pile resistance 29. This resistance 29, as indicated in Fig. 4, is connected in series with the coil 22a so that the acceleration is altered with the magnitude of the pressure on the pedal.

In order to make it possible for the driver to keep also intermediate positions with safety, the coil 22a is disconnected on attaining the desired intermediate position. The excitation of the coil 22 is then so large that the corresponding pole tooth 26 is safely held with further decreasing motor current. In order to be able to disconnect the'coil 2211, the pedal is made in the two parts I9 and 2|) which are mounted for limited pivotal movement relative to the other part of the pedal arm about a common pivotal axis 33. These levers I9 and 20 operate respectively control switches 3| and 32, which switches are normally biased open by pressure springs 33, only one of which is shown. During starting, the foot rests on both plates l9 and 20 so that both switches 3| and 32 are closed by this slight pivotal movement about the axis 3%. A suitable construction of these foot plates is represented in Fig. 3. A slight movement of the foot can release the foot plate I9 at any instant, whereby the switch 3| is opened and the coil 22a is thereby deenergized.

The switch 32 is closed when the pedal 2|! is depressed and thereby closes the circuit for the operating coil 34 of the circuit breaker 35, Fig. 4. As shown in Fig. 4, the circuit breaker 35 closes the main circuit breaker through the starting resistance 36, the motor armature 37, the field 38, and the coil 22. When the foot is taken oif the control lever 20 this circuit is interrupted by the opening of the switch 35. It will be understood that the control drum I3 is provided with suitable contacts for short circuiting in steps the starting resistance 36 as desired.

Furthermore, the switch drum for the electric braking may be provided with the same automatic stepping device.

In the modified form of the invention shown in Fig. 6, the magnet wheel 39 is connected to the drum 40 through a change speed gearing 4| arranged to operate the magnet wheel at higher speed than the drum. In other words, the magnet wheel 39 makes several revolutions during the progression of the drum 40 with the result that the effectiveness of the magnetic locking action is multiplied and increased.

Fig. '7 shows a shunt magnet coil 42, corresponding to the coil 22, which is arranged to be energized by a motor current responsive relay 43. This relay opens to deenergize the coil 42 when the motor current drops to a predetermined value.

While I have shown a particular embodiment of my invention, it will be understood, of course, that I do not wish to be limited thereto, since many modifications may be made and I, therefore, contemplate by the appended claims to cover any such modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. The combination with a control device, means for driving said control device, a magnet coil, a rotary magnet core member provided with a plurality of pole pieces, a driving connection between said rotary member and said control device, a stationary magnet core member c0- operating with said rotary member, said magnet coil being arranged to excite said rotary and stationary core members, and means for energizing said magnet coil in accordance with the current in the circuit of said control device so that said rotary member is released for rotation of said control device when the current reaches a predetermined value, and a second winding associated with said magnet coil and acting in opposition to said magnet coil.

2. The combination with a step by step control device, an operating member, a spring connection between said operating member and said control device for driving said control device, a magnet coil, a rotary member provided with a plurality of pole pieces, a driving connection between said rotary member and said control device, a stationary member cooperating with said rotary member, said magnet coil being arranged to excite said rotary and stationary members, and means for energizing said magnet coil in accordance with the current in the circuit of said control device so that said rotary member is released for rotation of said control device when the current falls to a predetermined low value, and a second winding associated with said magnet coil and acting in opposition to said magnet coil,

3. The combination with a step by step control device, an operating member, a spring connection between said operating member and said control device for driving said control device, a magnet coil, a rotary field structure for said magnet coil provided with a plurality of pole pieces, a stationary field structure for said magnet coil, a driving connection between said rotary field structure and said control device, means for energizing said magnet coil in accordance with the current in the circuit of said control device so that said rotary field structure is released for further rotation of said control device when the current falls to a predetermined low value, and a second winding associated with said magnet coil and acting in opposition to said magnet coil.

4. The combination with a motor, of a rotary switching device for accelerating said motor, a pedal, a spring connection between said pedal and said switching device for driving said switching device, a stationary magnet coil, a rotary armature for said magnet coil provided with a plurality of pole pieces, a driving connection between said armature and said switching device, means for energizing said magnet coil in accordance with the current in the circuit of said motor so that said armature is released for further rotation of said switching device when the motor current falls to a predetermined low value, and a second winding associated with said magnet coil and acting in opposition to said magnet coil.

5. The combination with a step by step control device, an operating member, a spring connection between said operating member and said control device for driving said control device, a magnet coil, a field structure for said magnet coil provided with a plurality of pole pieces, a stationary field structure for said magnet coil, a driving connection between said rotary field structure and said control device, means for energizing said magnet coil in accordance with the current in the circuit of said control device so that said rotary field structure is released for further rotation of said control device when the current falls to a predetermined low value, a second winding associated with said magnet coil and acting in opposition to said magnet coil, and means operated by said operatng member for varying the excitation of said second winding.

6. The combination with a motor, of a rotary switching device for accelerating said motor, a pedal, a spring connection between said pedal and said switching device for driving said switching device, a stationary magnet coil, a rotary armature for said magnet coil provided with a plurality of pole pieces, a driving connection between said armature and said switching device, means for energizing said magnet coil in accordance with the current in the circuit of said motor so that said armature is released for further rotation of said switching device when the motor current falls to a predetermined low value, a second winding associated with said magnet coil and acting in opposition to said magnet coil, and means operated by said pedal for varying the excitation of said second winding.

7. The combination with a step by step control device, an operating member, a spring connection between said operating member and said control device for driving said control device, a magnet coil, a field structure for said magnet coil provided with a plurality of pole pieces, a stationary field structure for said magnet coil, a driving connection between said rotary field structure and said control device, means for energizing said magnet coil in accordance with the current in the circuit of said control device so that said rotary field structure is released for further rotation of said control device when the current falls to a predetermined low value, a second winding associated with said magnet coil and acting in opposition to said magnet coil, and means operated by said operating member for deenergizing said second winding.

8. The combination with a motor of a rotary switching device for accelerating said motor, a pedal, a spring connection between said pedal and said switching device for driving said switching device, a stationary magnet coil, a rotary armature for said magnet coil provided with a plurality of pole pieces, a driving connection between said armature and said switching device, means for energizing said magnet coil in accordance with the current in the circuit of said motor so that said armature is released for further rotation of said switching device when the motor current falls to a predetermined low value, a second winding associated with said magnet coil and acting in opposition to said magnet coil, and means operated by said pedal for deenergizing said second winding.

9. The combination With a step by step control device, an operating member, a spring connection between said operating member and said control device for driving said control device, a magnet coil, a rotary field structure for said magnet coil provided with a plurality of pole pieces, a stationary field structure for said magnet coil, a driving connection between said rotary field structure and said control device, means for energizing said magnet coil in accordance with the current in the circuit of said control device so that said rotary field structure is released for further rotation of said control device when the current falls to a predetermined low value, a second winding associated with said magnet coil and acting in opposition to said magnet coil, means operated by said pedal for varying the excitation of said second winding, said pedal being constructed in two independently movable parts arranged to be simultaneously depressed and one of said parts being arranged to be released independently of the other, and switching means operated by said part when said part member is released for deenergizing said auxiliary coil.

10. The combination with a motor, of a rotary switching device for accelerating said motor, a pedal, a spring connection between said pedal and said switching device for driving said switching device, a stationary magnet coil, a rotary armature for said magnet coil provided with a plurality of pole pieces, a driving connection between said armature and said switching device, means for energizing said magnet coil in accordarms with the current in the circuit of said motor so that said armature is released for further rotation of said switching device when the motor current falls to a predetermined low value, a second winding associated with said magnet coil and acting in opposition to said magnet coil, means operated by said pedal for varying the excitation of said second winding, said pedal being constructed in two independently movable parts arranged to be simultaneously depressed, and one of said parts being arranged to be released independently of the other, and switching means operated by said part when said part memberis released for deenergizing said auxiliary coil.

OTTO WiiNscHE. 

